Given an Expression which is represented by String. The task is to find duplicate elements in a Regular Expression in Java. Use a map or set data structures for identifying the uniqueness of words in a sentence.
Examples:
Input : str = " Hi, I am Hritik and I am a programmer. " Output: I am Explanation: We are printing duplicate words in the given Expression. Input : str = " Ironman is alive. " Output: There is no Duplicate Word. Explanation: There are no duplicate words present in the given Expression.
Approach 1:
- Get the Expression.
- Store all Words in an Array.
- Splitting word using regex ‘\\W’. (use of regex)
- Iterating in the array and storing words and all the number of occurrences in the Map.
- Now, In the Map, If the number of occurrences is more than 1 then we are printing the word.
Below is the implementation of the above approach:
Java
// Find Duplicate Words in a Regular Expression in Javaimport java.util.*; public class GFG { public static void main(String[] args) { // we have a expression String expression = "Hi, I am Hritik and I am a programmer"; // splitting words using regex String[] words = expression.split("\\W"); // we are creating a Map for storing // strings and it's occurrence" Map<String, Integer> word_map = new HashMap<>(); // Here we are iterating in words array and // increasing it's occurrence by 1. for (String word : words) { if (word_map.get(word) != null) { word_map.put(word, word_map.get(word) + 1); } // if the word came once then occurrence is 1. else { word_map.put(word, 1); } } // creating a keyset of word_map Set<String> word_set = word_map.keySet(); // We are iterating in word set for (String word : word_set) { // if word matched then checking occurrence if (word_map.get(word) > 1) // here we are printing the duplicate words System.out.println(word); } }} |
Output
I am
Approach 2:
- Get the Expression.
- Store all Words in an Array.
- Splitting word using regex ‘\\W’. (use of regex)
- Matching every word of the array with other words through iteration.
- If words matched then adding words in a Set because set removes the repeated words added by the flow of iteration.
- Finally, we are printing the set.
Below is the implementation of the above approach:
Java
// Find Duplicate Words in a Regular Expression in Javaimport java.util.*; public class Main { public static void main(String[] args) { String expression = "Hi, I am Hritik and I am a programmer"; // splitting words using regex String[] words = expression.split("\\W"); // creating object of HashSet class implemented by Set<String> set = new HashSet<>(); // here we are iterating in Array for (int i = 0; i < words.length - 1; i++) { for (int j = 1; j < words.length; j++) { // if strings matched then adding strings in // Set because if we ad same string set will // remove one and we have only repeated // words. if (words[i].equals(words[j]) && i != j) { set.add(words[i]); } } } // here we are printing the set System.out.println(set); }} |
Output
[I, am]
